Auxiliary train signal system



y 1951 R. J. HERBOLD 2,554,906

AUXILIARY TRAIN SIGNAL SYSTEM Filed June 25, 1846- 52 Fgrl.

T 62 la 4 Z5 26 a2 a1 f1 W53 I 3nnentof Roberf J, Herbolcl witness CQH'FQ Herbevi coveJ i affomeg Patented May 29, 1951 OFFICE AUXILIARY TRAINSIGNAL SYSTEM Robert J. Herbold, Denver, 0010., asslgnor to Lafayette M.Hughes, Denver, Colo.

Application June 25, 1946, Serial No. 679,298

Claims. (01. 246-177) This invention relates to railway signal apparahasand more particularly to apparatus which will warn the engineer that ared or danger signal has been set against his passage into the railwayblock.

Railroad accidents may result from the engineer passing a red light or a'semaphorestop' signal, and this is often due to the signal beingimproperly located or'obscured by dense fog or storm conditions, or itmay not'be seen by the engineer because of 'duties which' distract'his'attention. It is desirable to provide an audible or visual signal withinthe engine cab which gives the required indication of the condition ofthe track ahead, Many schemes have been proposed or tried, such as an"induction system associated with therails and an external source ofpower which duplicates the appearance of the block signals within theengine c'ab. Such Systems are, however, very expensive and are notinfallible under the many operating conditions required, and they areemployed simply as a double check on the engineer's vision of theoutside signal. This system is particularly vulnerable to externalconditions such as rain or snow, and it requires a high powerconsumption. Any supplemental signal system should not draw heavily onthe existing storage batteries of the standard signal systern.

The primary object of this invention is to provide an apparatus whichautomatically warns the engineer within the locomotive cab that thetrack is not clear ahead and that a stop signal has been set against hisentering the block.

A further object is to provide a warning signal construction which doesnot require excessive power consumption and which gives the requiredsignal on the train only while the train is passing through a limitedextent of travel.

A further object is to provide such a system in which the signal isrendered operative b the passage of the train and is inoperative at allother times. Other objects will be apparent in the following disclosure.

In accordance with my invention, I have provided a photronic signalsystem on the train which is activated by light governed in accordancewith the setting of the track signal and wherein the light is in turnrendered eiiective by the approach of the train thereto.

Referring to the drawings:

Fig. 1 is a diagrammatic plan of the electrical circuits located nearthe track and showing the relationship of the signalling devices to theasso- 'ciated mechanism on. the loc mot ve; and

Fig. 2 is a diagram of the electrical circuits on the locomotive whichprovide the train signal.

The preferred embodiment of this invention comprises a photo sensitivecell mounted on the train and arranged to be activated b a light locatednear the track which shines only when the railway signal is set fordanger, as is caused by raising a semaphore arm or energizing a redlight or as desired, and only when the train is approaching the warningsignal. The apparatus comprises essentially a light I ll arranged tothrow a beam across the track towards a passing train which willactivatea photosensitive cell I2 on the train, and the cell is in turnconnected electrically to give a required signal or warning indicationfor the guidance of the engineer. The signal light I0 is suitablylocated relative to the railway semaphore or red and green light signalsystem 4|, such as near or on the signal tower as illustrated, or at asuitable distance therefrom. The light I 0, which may comprise anelectric light bulb of suitable power and a reflector or condenser toconcentrate the beam, is located at such an elevation that it willactivate the photosensitive element I2 carried on the side of the trainwhen the latter passes the light beam.

The photoelectric cell 12 may comprise a photoemissive tube of the typeof the General Electric Argon gas filled PJ23 tube which is sensitive tothe visible spectrum and infra red wave. In such a photoemissive tube,the anode may be a vertical wire and the cathode may comprise asensitive coating of caesium on caesium oxide carried by a base ofsilver metal. Since such tubes may be not sufiiciently rugged towithstand the violent vibrations of a locomotive, I prefer to use aphotoconductive type of cell, such as an Eby type R100, which has itselectrical resistance decreased by light activation, and particularly byinfra red rays. Such a photoconductive cell may have a ribbon of asuitable light activated resistance material, such as selenium, arrangedbetween two electric terminals to provide the required conductivity of acurrent from a source of potential, such as a 6 volt or other lowvoltage battery, The cell may be connected in series with a suitablesensitive relay arranged to control a secondary load or signal circuit.The photosensitive cell l2 (Fig. 2) may be mounted within an opaquecasing l4 having a long projecting tube l5 adapted to receive only anarrow pencil light or ra from the lamp In so that the sensitive elementmay not be activated by ambient or extraneous light.

The light receiving and signalling system on .the locomotive or trainmay be of various constructions for the purpose of giving the requiredsignal. The simplified form shown in Fig. 2 involves the Ebyphotoelectric resistance cell l2 connected in series with a 6 voltbattery it and a variable resistance ll of about 25 ohms and with thesolenoid of a rela l8 arranged to operate a switch I9 against thepressure of a spring 20 and thus close the circuit through a battery 2|with an electric bell 22 and a signal light 23 arranged in series withthe battery. Many con structions may be employed to give the requiredsignal to the engineer, whether audible or visual. The system may besuch that the signal 23 has lights arranged vertically as a clear tracksemaphore signal at all times unless the photocell l2 clear. The holdingrela may be of many types of construction, such as the standard dash-pottype in which the movement of a piston is delayed by fluid flowing underspring pressure through a small orifice. Operation of the solenoid 33causes the piston to move against spring pressure to a is activated, inwhich case the relay throws a circuit to show a horizontal red lightsignal; or a steady white light may be interrupted by operation of therelay and a red light thrown on.

It is desirable that the strong light in mounted on the ground, whichactivates the photoelectric cell l2 on the locomotive, be lighted onlywhile the signal is required; i. e., when the train is passing. For thispurpose, I propose that a device on the engine serve to connect the lampHi to its source (if power only while the engine is passing from aninitial light exciter position to one where the photoelement l2 may beactivated. Various types of mechanical switches may be placed near thetrack for operation by a lever arm moved down by the wheels of thelocomotive; but such constructions are subject to interference by snowor have other disadvantages. I, therefore, prefer to employ aphotoelectric device which is excited by a beacon light carried by thelocomotive.

This beacon system may comprise an electric light 25 carried on theengine or train in a suit able concave reflector 2 6, or associated witha condenser lens to concentrate the light beam. The lamp 25 need nothave a very high candle power and it may be operated continuously by aseries connection with the battery l9, as illustrated in Fig. 2. Thisbattery may be replaced by a small generator on the locomotive, or thepower may be derived from the train electrical system. Mounted on theground at a suitable distance in advance of the signal light II! (whichis to be duplicated at both sides thereof) is a photoelectric element 30arranged to control the light I0 and cause it to shine while the engineis moving past. This trackside phototube 30 may be of any desired type,such as a photoemissive tube, as above described, or a Westonphotovoltaic cell. If a photoconductive selenium cell or a photoemissivetube is employed, then a suitable battery 3| is arranged in the circuitthat connects the photoelement with a suitable amplifier 32, Theamplifier 32 controls a relay solenoid 33 which operates amake-and-break switch 34 that governs another circuit to connect thebattery 35 with the light Hi.

It is required that the light I0 shine for several seconds or for adelayed period of time after the photoelectric element 30 has beenactivated and has completed closure of the switch 34, or until thephotoelement .l2 reaches the line of light from lamp H1 at the signaltower. For this purpose I may employ a holding or delay relay 4!! inassociation with a further relay switch system which permits the lightIn to shine only if the standard railway tower signal at 4| is red orotherwise indicates that the track ahead is not position where thespring thereafter causes the piston to move slowly while the fiuid isescaping and the circuit remains closed until the piston has reached itsinitial open circuit position.

The construction of the relay 40, as illustrated, comprises a solenoid42 arranged to move a switch arm 43 against the action of a spring 44and make the circuit through battery 35 with the lamp Ill. The delayfeature of this construction, which may be of standard type, comprisesin general a bi-metal latch 45 which springs into place and holds theswitch arm 43 locked in position until a heater coil 45 surrounding thebimetal latch expands the latch metals difierentially enough to springthe latch away from the switch arm and allow the spring 44 to break theconnection. A supplemental circuit including a variable resistance 41 isarranged to pass current through the heater coil of the latch while thecircuit is closed. A suitable resistance 65 in the light circuit insuresa proper division of the current between the light and heater coilcircuits. It will be understood that any suitable delay mechanism may beemployed for this general purpose, provided it will hold the lamp I0lighted for such period of time as is required for the train to passfrom the position of activating the phototube 30 to that of having itsphototube l2 activated by the light 10. After the proper signal has beengiven to the engineer in the cab, the time delay mechanism at the signaltower on the ground is no longer needed. It is also feasible to place aholding relay in the circuit of the electric light 23 and bell 22 in theengine cab, so that the signal will remain operative for considerabletime. I may, however, provide a latch 48 in the engine cab which holdsthe connection of the switch I9 closed until the engineer manuallyreleases the same. This simplified construction, as illustrated, mahowever be replaced by more elaborate or desired mechanism which willeffect the required purposes.

The circuit to lamp It] should be made only if the red or danger signalis showing at the switch tower 4!. This is accomplished by asupplemental relay switch in the holding relay system. As shown, the redsignal light 50 and the green signal light 5| are mounted in series witha battery 52 for actuation of either light as required by the railwaysignal system. Suitable switches and controls will be provided to givethe required red or green signal at the tower. If the green signal G ison, then a circuit is made with the lamp 5| and battery 52 through thewires 53 and the switch arm 55 that is held against the relay contactwire 56 by spring 57. This breaks the circuit between contact 58 and theswitch arm 55 which is also connected through battery 56 and switch 34with the solenoid 42 of the holding relay 40. Therefore, any activationof the cell 30 by the exciter lamp 25 on the locomotive will beineffective to turn on lamp Hi.

When the red light 50 is to be displayed at the signal tower, theoperator throws a switch 60 in a supplemental system including asolenoid 5i and a battery 63, thus energizing the solenoid and pullingdown the relay armature 55, This breaks the green light circuit throughthe armature, 55 and contact 56 and makes a circuit through the'c'ontact62 and the battery 52 to turn On-the-red light 50. At the same time aconnection is made between contact 58 and the arm- 55,which is incircuit with the winding of the relay solenoid 42, so that when therelay 3 4 has been closed by activation of cell 30 by light on the traina circuit is made through battery 66- which closes the switch 43 andturns on the trackside'light 3. Thus, the two relay control devices 6 l55 and. 33, 34 which are governed respectively by setting the tracksignal and by activating the track-side element act in series to insurethat the light Ill can be energized only when the red signal 50 has beenset and the train light 25 is passing the element 30. Hence, the enginecab signal can be given only under these two precedent conditions. Also,this lighting of lamp l0 lasts only while the relay switch 40 permitsit. Hence there is only a very small consumption of power, and acomparatively high wattage lamp [0 may be used without drawing heavilyon the battery 35. Various other advantages are inherent in the system.For example, the construction on the engine is very rugged and willwithstand severe vibrations. The apparatus mounted on the ground or atthe tower may be made as delicate as desired, since it is not subject tovibrations.

Since the photo elements are sensitive to infra red light which passesreadily through rain, fog and snow, the signals will be received by thelocomotive engineer within the cab even if he cannot see the signal onthe outside. Various expedients may be adopted to prevent the ambient oroutside light from interfering with the signal system.

The operation of this auxiliary train signal apparatus gives a warningon the train of a signal that has been set by the standard railway tracksignalling semaphores or red and green light system. The preferredconstruction comprises a photo element on the train and apparatus, suchas a signal bell or light, which is governed by the photo element, sothat the apparatus is energized when the element is activated by a tracklight arranged near the track and close to the passing train and at sucha height and direction of pointing that a beam therefrom will illuminatethe photo element. The track light is maintained in an oil condition,except when required to give the train signal, because its power circuitcan be completed only when a predetermined railway track signal has beenset. Changing the track signal to red closes a switch in a power circuitwhich remains in that condition during the entire period that this redsignal is displayed. The light It), however, it not energized by itspower circuit until a second switch is closed, and that switch isgoverned by the passing train. This is preferably effected by thephotocell 30 arranged near the track and in advance of the track lightIt, relative to the direction of train travel. When this cell 30 isactivated by a light 25 on the passing train, it serves through itsamplifier and a supplemental relay system 34 to actuate a holding relay40, provided the switch 55, 58, that is controlled by manipulation ofthe track light system, has been previously closed. This completes anelectrical circuit for supplying power to the track light [0, thusenergizing the photo element [2 when the latter reaches the ppsition ofpassing that track light, and giving the danger warning on the train.That train signal may be maintained in an on condition by a holdingrelay or by any other suitable device for a reasonable length of time.

It will be appreciated that the electrical circuits and associatedapparatus may be changed materially, provided the apparatus operates inaccordance with the principles above set forth. Hence the abovedescription is to be interpreted as describing those principles and apreferred embodiment of the invention and not as imposing limitations onthe claims appended hereto.

I claim:

1. In combination with a railway track signal and means for setting it,an auxiliary train signalling apparatus for giving a warning of thesignal set against a train comprising a photosensitive element and anelectrical signalling device governed thereby which are mounted on thetrain, a trackside light fixed relative to the track signal foractivating said photo element as the latter passes it, a normally brokenelectrical power circuit for energizing the trackside light, a tracksidephotosensitive element located in advance of the trackside lightrelative to the train travel, means including a light on the train foractivating said trackside element as the train passes it, and normallyinoperative electrical apparatus including two control devices governedrespectively by activation of the trackside element and by setting thetrack signal which completes said power circuit for energizing thetrackside light after the track signal has been set and the train lighthas activated the trackside element.

2. Apparatus according to claim 1 comprising a releasable time delaydevice controlling the trackside light circuit for prolonging the periodduring which the trackside light is energized and after the tracksidephotosensitive element ceases to be activated.

3. Apparatus according to claim 1 comprising a releasable holding deviceon the train which maintains the electrical signalling apparatuseffective to prolong the warning signal after the photosensitive elementon the train ceases to be activated.

4. In combination with a railway track signal light, an energizablecircuit therefor and controllable means for energizing the circuit anddisplaying the light, an auxiliary train signalling apparatus forwarning of the displayed light comprising a photosensitive element and asignalling device governed thereby which are mounted on the train, atrackside light fixed relative to the signal light for activating thetrain element as the latter passes the light, a power circuit for thetrackside light including a switch which is biased towards an openposition, a time delay device effective to releasably hold the switchclosed for a given period of time, a solenoid for closing said biasedswitch and rendering the time delay device elfective, a tracksidephotosensitive element fixed in ad- Vance of the trackside light, alight on the train to activate the trackside element when passing it, anormally open relay switch which is closed by activation of thetrackside element, a second normally open relay switch which is closedwhen the track signal light circuit is energized, and an electricalcircuit connecting said relay switches in series with said solenoid, sothat the train signalling device can be rendered operative by thetrackside light only while said controllable means causes the tracksignal light circuit to be energized and the track signal light to bedisplayed and after the train light has activated the trackside element.

5. Apparatus according to claim 4 comprising an electrically operatedsignalling device on the train, a power circuit therefor including aswitch which is biased towards an open position, a releasable device forholding the switch closed, and a solenoid governed by activation of thephotosensitive element which closes the switch and renders saidreleasable device efiective to hold the switch closed and prolong thesignal after the time of activation of said element. ROBERT J. HERBOLD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS France Oct. 1, 1906

